(2) Sunspots


Image courtesy of Big Bear Solar Observatory.

Click here to see what the sun's active surface looks like today?

Click here to see a recent image of its invisible surface magnetic field.

Basic Facts About Sunspots

Dark splotches on the sun, like the one shown in close-up, are sunspots. They are almost always seen in pairs and in groups of pairs.

Sunspots are dark because they are the coolest places on the sun. Magnetic fields about as strong as those of a horseshoe magnet (which is 1000 times stronger than the Earth's surface magnetic field) keep heat from flowing up to the surface here. The sun's differential rotation (faster at low than high latitudes is critical in producing sunspots).

Solar flares (enormous explosive releases of energy from the sun) are most likely to occur in sunspot groups that are growing rapidly and rotating like a hurricane. The number of sunspots on the sun at any given time varies in an ll-year cycle as does the number and severity of disturbances in space weather. Constantly monitoring the development of sunspot groups is one important job of spaceweather forecasters.



The source of this material is Windows to the Universe, at http://windows2universe.org/ from the National Earth Science Teachers Association (NESTA). The Website was developed in part with the support of UCAR and NCAR, where it resided from 2000 - 2010. © 2010 National Earth Science Teachers Association. Windows to the Universe® is a registered trademark of NESTA. All Rights Reserved. Site policies and disclaimer.